Analysis of acetylcholinesterase synthesis and transport in the rat hippocampus: recovery of acetylcholinesterase activity in the septum and hippocampus after administration of diisopropylfluorophosphate

The site and rate of synthesis, as well as the transport dynamics, of newly synthesized acetylcholinesterase (AChE) has been studied in the septum and hippocampus of the rat. Histochemical and biochemical techniques were employed to study time-dependent changes in AChE activity of the medial septal nucleus and hippocampus following systemic administration of the anticholinesterase diisopropyl-fluorophosphate. In both septum and hippocampus, an initially rapid phase of recovery was followed by a slower recovery with similar rate constants for the two regions. Analysis of AChE synthesis in the septo-hippocampal system revealed that recovery of activity in the septum(t 1/2for recovery= 140h) preceded that in the hippocampus(t 1/2for recovery= 400h). The data suggested that the bulk of septal AChE in the hippocampus is transported via the slow component of axoplasmic flow (about 2 mm/day). A fast component may exist, but the experimental arrangement did not permit the clear demonstration of any rapid axoplasmic flow.